Burner for gas turbine engine



Nov. 8,1966 1 KAPLAN 3,283,497

BURNER FOR GAS TURBINE ENGINE Original Filed July 9, 1963 5 Sheets-Sheet l J8 MG. 3'

/ fig 'O 29 w 87 51 K 46 66 o A INVENTOR. 65 0 Z KflPAA/V 70 R/VEY Nov. 8, 1966 L. 1. KAPLAN BURNER FOR GAS TURBINE ENGINE 5 Sheets-Sheet 2 Original Filed July 9, 1963 W mm N Y R A 1 M m p we wk 1 Nov. 8, 1966 L. I. KAPLAN 3,283,497

BURNER FOR GAS TURBINE ENGINE Original Filed July 9, 1963 3 Sheets-Sheet I5 INVENTOR. LEO Z K141 AM United States Patent 7 Claims. (Cl. (so-39.74

This application is a division of my copending application for United States Letters Patent Serial No. 293,603, filed July 9, 1963, entitled Gas Turbine Engine With Controllable Power Output, and which application is a continuation-in-part of application Serial No. 121,449, filed July 3, 1961, entitled Gas Turbine With Controllable Power Output, now abandoned.

The present invention is directed to a gas turbine engine of the general type disclosed in my Patent 2,914,918, granted December 1, 1959, disclosing a high efliciency gas turbine engine featuring serially connected combustion chambers arranged concentrically of one another between the turbo compressor unit and the power output turbine. The present invention incorporates various improvements over this earlier design and features, in particular, the use of simple easily controlled means for varying, in accordance with changing power demand requirements, the proportions of the compressed gases re quired to flow through the power output turbine without interfering adversely with the efficient operation of the turbo compressor, the combustion chambers proper or other components of the gas turbine.

It has been proposed heretofore to provide for variable power demands in a gas turbine engine by regulating the fuel supply to the combustion chambers while simultaneously throttling gas flow to the power turbine and bypassing the gases so throttled through a regulated passage circumventing the power turbine. Such a proposal is disclosed in United States Patent 2,473,356, granted to Rudolph Birmann, and is subject to certain shortcomings and disadvantages sought to be avoided by the present invention. For example, the referred-to prior teachings require the use of two butterfly-type valves one of which is located in a large bore circular duct leading into the upstream side of the power turbine and the other of which is located in an equally large bore bypass conduit discharging into the downstream side of the power turbine. Engine power output is cut off by reducing fuel flow and closing the first v-alve while simultaneously opening the bypass valve until all gas flow has been routed around the power turbine. By this technique the large volume flow of hot gases is gradually transferred from a path through the turbine to a path through the bypass conduit making use of massive dual valve structures and a bypass conduit as large as the main turbine input conduit.

The present invention seeks to avoid the many problems characterizing the foregoing prior control expedient by providing simple, compact, easily operated, lightweight and inexpensive pressure regulating means for regulating the effective pressure differential across the power turbine by bleeding gas past the turbine in the quantity required to obtain the desired power output and allowing the remainder of the hot gas to flow through the turbine without encountering interference, restrictions, obstructions or losses not experienced in normal full or substantially full power operation. It is found that this unique expedient of' reducing the pressure drop across the power turbine by bleeding regulated quantities of either hot or cold gas or portions of both into the downstream side of the power turbine provides highly flexible, easily and infinitely variable control of the power output extending from no load to full load. Of particular importance is the fact that this mode of control is obtainable almost instantaneously, particularly when reducing the pressure differential by bleeding off cold gas with the fuel supply properly throttled. In connection with the foregoing, it is pointed out that, desirably, provision is provided for regulating the pressure across the turbine by bleeding gas into the downstream side of the turbine circuit from either the upstream or downstream side of the combustion chamber for the turbine, or partially from both sides as desired for most effective results under any given operating situation.

The significance of the foregoing will be readily recognized by persons familiar with the adverse starting load conditions of gas turbine engines and the sensitivity of rotary compressors to surging and pulsing under changing load and temperature conditions. The present invention is characterized by two highly important additional capabilities by reason of the regulatable bypass port or ports provided around the power output turbine- If one or more of these pressure regulating or bypass ports are open, controlled amounts of corn-pressed air or gas are bypassed past the power turbine with the result that, during starting conditions for example, the only load imposed is but that required to drive the compressor.

In addition and during normal operation of the engine, it is known that compressor performance is typically close to unstable conditions wherein pulsing, surging and the like inetficient flow conditions can occur. This is due in major part to the tendency of the air to backflow if restriction to air flow increases beyond critical values as can easily occur because of high ambient air temperatures, or because high operating temperatures internally of the engine. Compensation for these and other factors conducive to unstable compressor operation is provided in a simple and effective manner by this invention in the form of regulatable bypass port means for stabilizing compressor performance and the air handling capability of the engine Without need for changing the turbine nozzles, the engine porting, or the compressor structure in any respect. Desirably two independent bypass port means are provided, one such means being sized at the time of engine manufacture to adjust the particular engine to a desired balanced condition for optimum performance under specified conditions. The second type of porting means is regulatable at will to vary the engine output between no load and full load output. It is also pointed out that the first or compensating port means may be provided with control means thereby to accommodate the engine to changing climatic or other variables adversely affecting compressor stability and performance.

Coupled with the regulatable bypass means for the power output turbine are separate and independently regulatable fuel supplies for the two combustion chambers. The fuel supply control includes provision for operating either combustion chamber independently of the other or both chambers simultaneously under substantial and full load conditions. Because of the unusual flexibility of combustion chamber operation forming a feature of the invention taken together with the arrangement of these chambers relative to one another and other components of the engine, there is provided an engine of unusual flexibility and versatility.

For example, the engine is normally started using only the inner combustion chamber, the fuel requirements of Patented Nov. 8, 1966 instantaneous starting as soon as fuel is admitted. If

only the inner combustion chamber is functioning, the relatively cold compressed air delivered by the compressor is not effective to drive the power turbine even though the bypass passages are closed. It is also pointed out considerable saving in fuel for normal mid-range power requirements and enables the operator to meet heavy power requirements simply by bringing theouter combustion chamber into operation.

Another characteristic feature of the present design is the fact that the products of combustionfrom both combustion chambers are required to discharge through the turbine drive means for the engines air compressor.

'By virtue of this arrangement both combustion chambers and, the power output turbine are maintained under pressurized conditions at all times irrespective of wide variations in engine load and even when the engine is operating without load. Owing to the separate, and easily adjusted fuel supplies for the separate combustion chambers and to the provision of the simple means herein provided for controlling the output of the power turbine, the turbo compressor assembly operates at high efiiciency and is in instant readiness to respond to varying operating requirements with maximum speed and sensitivity.

, Another feature of the design is the concentric relationship of the two principal combustion chambers to the end that these operate withmaximum thermal efliciency at all times During low or no load requirements of the output turbine all or the major portion of theturbo compressor power requirements can be supplied by products of combustion generated principally or entirely within the inner combustion chamber.

Another problem attending the operation of gas. tur-,

bine engines, and particularly troublesome under Wide rangepower conditions, concerns the supply of, fuel to the combustion facilities. Heretofore, costly precision fuel. nozzles have been essential to introduce fuel in properly atomized condition into the fast flowing combus tion air. Despite diligent efforts designers have been 1111- able toprov'ide a trouble-free design or one capable of using a widerange of fuels, or one not subject .to malfunction by the presence in the fuel of foreign matter not easily removed by inexpensive filtering expedients.

This invention entirely. avoids. these andot-her vexing problems of prior fuel supply designs by providing an in expensive fuel feeding'systemjfeaturing ahigh tempera ture wicking assembly mounted directly in the combustion chamber and operating to dispense uniformly distributed fuel vapor into the air within the combustion chamber or flowing thereto and: generated within the wicking from pressurized liquid fuel supplied-to the wicking. The Wicking proper is simple, easily constructed, inexpensive and of'particular significance, usable with equalefiiciency and nonclogging trouble-free effectiveness with both high and low grade fuels. 7

. Still another feature is the provision ofimproved means for cooling the engine bearings as well as the hub of the compressor turbine runner. To this end compressed airis circulated over the turbo-compressor bearings as well as over the surface of .turbine runner means driving the, compressor. Heat dissipating fins applied to the bearing housing for the main power. turbine are highly effective in cooling these hearings.

The gas. turbine engine of the present invention is ideally suitedfor a great variety of prime mover power applications, whether of a stationary or nonstationary nature. Owing to the simplicity and ease with which the power output turbine can be activated and deactivated, there is'no need-for the usual clutch or thelike disconnect between the turbine and the load proper. Instead,

a 4 the function of the clutch is served in the present design by adjusting a simple valve mechanism functioning to route varying amounts of the products of combustion. through the power output turbine to satisfy power requirements, and to bypass substantially all gas and prodnets of combustion. around the power output turbine under idling or no load conditions thereby rendering the latter ineffective to drivethe load. Alternatively, and

operating speeds with the result that the engine. may be.

operated at partial power output for long periods without adverse effects. Disconnection of the power output turbine is also achieved by operating the fuel control to dis.- continue fuel flow to the outer or primary combustion chamber. This chamber then cools rapidly and ceases to. supply gas adequately heated to drive the power output turbine. In this connection itis pointed out that a con: siderably smaller volume of compressed air is produced when the hot gasempl-oyed to drive the compressor is restricted to that produced. by the inner combustion chamber; 2

Still another feature of importance is the use of a single stage centrifugal compressor having an axial flow inlet and' an axial flow outlet as Well as a shroud embracing the outer peripheries. of its blades. By the use of a compress-or of this type a high efiiciency gas turbine engine is achieved, of unusual compactness and of uniform exterior dimensions throughout its length.

Accordingly, it is a primary object of the present invention to provide a new and improved gas turbine. engine of unusually simple and compact design featuring a direct positive driving connection at all times between the engine and the load and capable of being easily reg:

ulated between no load and full load output with minia mum lag and with minimum interference with the overall engine operating efficiency.

Another object of the invention is the provision of an improved method of generating power and controlling the useful output thereof. 7

Another object of the invention is the provision .of a. gas turbine engine having means for" activating and de-.

activating the, power turbine thereof While maintaining the air compressor in operation under substantially the same conditions prevailing during normal load conditions.

Another object of theinvention is the provision of improved means for vaporizing anddistributing fuel. into hot gas generating chamber ofahot gas engine.

, Another object'of the invention is the provision of a] high temperature vapor generator adapted to be located interiorly of a hot gas generator for a. gas turbine engine.

Another object of the inventionis the. provision of a high temperature fuel feeding Wick designed to operate interiorly of a hot gas generating chamber and featuring unique means for distributing pressurized liquid fuel to all parts of the wick and equally effective with a wide Referring now to the drawings in which a preferred.

embodiment of the invention is illustrated.

FIGURE 1 is a generally schematic view of an engine according to the present invention shown directly and positively connected to a typical load such as thedifferential of a Wheeled vehicle;

FIGURE 2 is a longitudinal sectional view on an en larged scale through the engine proper showing the parts positioned for full power output;

FIGURE 3 is a cross-sectional view taken along line 33 on FIGURE 2 showing construction details of the heat exchanger utilizing the exhaust products of combustion to preheat compressed air en-route to the combustion chambers;

FIGURE 4 is a diagrammatic showing of a preferred embodiment of the fuel and power control mechanism;

FIGURE 5 is a diagrammatic view of the manually controlled fuel valve in its four principal positions; and

FIGURE 6 is a fragmentary longitudinal sectional view through one of two similar vvick devices employed in each of the combustion chambers.

Referring more particularly to FIGURES 1 and 2 there is shown a preferred embodiment of the present invention wherein a gas turbine engine, designated generally 10, is shown supported in a suitable manner in the engine compartment of a vehicle 11. The power output shaft 12 of engine is connected through suitable speed reduction means 13 to conventional drive shaft assembly 14 connected through the usual differential 15 with the rear axles of vehicle 11. It is pointed out and emphasized that a clutch is not required and that movement of the vehicle is controlled by manipulation of a suitable forward and reverse drive control 16 forming part of the speed reduction means 13 and by suitable foot or manu ally controlled means 17, 17 for controlling respective by-pass valve means to be described presently and associated with the power output turbine of engine 10. Additionally, an alternate or supplemental control selectively usable along with or independently of means 17, 17 comprising manually controlled valve mechanism 110 for the engine fuel supply is effective in the ellicient control of engine operation and power output as will be explained in detail below.

Referring now more particularly to FIGURE 2, it will be understood that turbine engine 10 comprises an elongated cylindrical outer housing 18. Fixedly secured, as by nut 19 to its output shaft 12, is one or more runners 20 of a reaction or impulse turbine constituting the power output turbine of the engine. Shaft 12 is suitably supported by anti-friction bearings 21, 22 at the opposite ends ofa supporting hub 23 projecting axially from the toroid shaped end cap 24 for the left hand end of engine housing 18, as viewed in FIGURE 2.

Since bearings 21, 22 are closely adjacent the hot power turbine, provision for cooling these is highly desirable and is accomplished by heat radiating fins 23 integral with or bonded to hub 23. The generally vertical disposition of these fins facilitates circulation of cooling air past the fins by convection. Air scoop means can also be used advantageously to provide forced air circulation.

Concentrically supported within the right hand end of engine housing 18 is a turbo-compressor assembly desig nated generally 25. This assembly includes a shaft 26 which is shown as aligned with and operatively dissociated from engine output shaft 12. However, it is to be understood that these two subassemblies need not be aligned but in fact may be disposed in any desired nonaligned relationship. The opposite ends of shaft 26 are supported in bearing assemblies 27, 28 mounted at the opposite ends of a tubular housing 29. A turbine drive runner 31 is held assembled to the left hand end of this shaft by a nut 32. Similarly secured by nut 33 to the opposite end of shaft 26 is a centrifugal type compressor impeller 35 having radially disposed blades 36. Preferably, the impeller is so designed that the velocity of air passing along the passages thereof continually decelerates as it passes therealong to the point of discharge into diffuser 44. The outer radial edges of blades 36 are rigidly secured to and closed by an annular shroud 37, which is highly effective in reducing friction and other losses of air undergoing compression. Shroud 37 encloses the major portion of the blades and particularly the discharge end thereof where the direction of air flow is being di rected to flow axially along the interior surface of cylin drical housing 18 of the engine and into the outer combustion chamber. As will be appreciated, except for shroud 37, the rapidly flowing air undergoing compression would be flowing through a long spiral path in direct contact with the inner surface of end cap 39. The shrouded impeller employed in the present invention avoids these high friction and turbulence losses and accounts in large measure for the high performance of the air compressor and the fact that a single-stage centrifugal compressor meets the air requirements of the engine disclosed herein. By employing an impeller diameter substantially as large as the outer shell of the engine, it is feasible to drive the compressor at lower speed.

The circular webs supporting the bearings for the opposite ends of turbo compressor shaft 26 are provided with a ring of closely spaced air ports 41, 41 which serve to pass a sufiicient quantity of cool air to cool bearings 27, 28 as well as the hub of turbine runner 31. This cooling air is bled from the discharge rim of the compressor impeller, through ports 41 closely beside bearing 28 to cool that hearing, thence along housing 29, through the ring of ports 41, adjacent bearing 27 and then radially across the surface of turbine runner 31 and into the gases discharging from the blades of this runner. As will be recognized, the degree of cooling is controlled primarily by the flow of cooling air permitted by the size and number of bleeder ports 41.

The right hand end of housing 18 and the compressor rotor in particular are enclosed by an end cap 39 having a streamlined air intake end 40 opening axially of the engine. The larger diameter outlet end of end cap 39 is secured to engine housing 18 in any suitable manner and cooperates therewith in directing the compressed air axially of the engine.

It will be understood that compressor impeller 35 discharges axially of the engine, as is indicated at 42, into a stationary diffuser ring 43 provided with the usual stationary diffuser blades 44 of well known appropriate design. The latter serve to effect the eflicient transition of the air from discharge passages 42 of compressor impeller 35 into the annular chamber 46 lying immediately inside the right hand end of housing 18. The outer wall of chamber 46 is formed by housing 18 whereas its inner annular wall is provided by a sheet metal shell 47 substantially coextensive in length with outer housing 18 and serving to divide the inner or secondary combustion chamber 48 from the outer or primary combustion chamber 49.

Important advantages and increased efliciency is obtainable by arranging combustion chambers 48 and 49 concentrically of one another intermediate turbo-compressor assembly 25 and the power ouput turbine here represented by runner 20. The two combustion chambers will, therefore, be recognized as separated from one another by the intervening common cylindrical shell 47 of heat conducting material and by a perforated liner shell 47a suitably secured to the shield or cap 47b for turbine runner 20. It will be understood that shell 47a is not essential and may be dispensed with if desired particularly if suitable flame holding means are present for the secondary combustion chamber.

There is preferably disposed within the outer or primary combustion chamber 49 a so-called basket formed by a pair of annular shells 50, 50 interconnected at their right hand ends by an annular ring 51 of conical shape in crosssection, the walls of these shells each preferably being provided with a large number of air inlet openings 52 in accordance with customary practice. Shells 50, 50 are suitably supported concentrically of shells 18 and 47 as by means of radially disposed spacer struts 53. The spacing of walls 50 from walls 47 and 18 permits compressed air to pass freely along the outer side of these walls to provide desirable heat insulation with part of the air entering chamber 49. through openings 52, and part flowing past this chamber and into secondary combustion chamber 48.

Hot products of combustion and unconsumed combustion air normally exhaust from primary combustion chamber 49 and through the toroidal return bend annulus formed in end cap 24 and through nozzles provided by an appropriately designed annular row of blades 55. Blades 55 direct the hot products and unconsumed compressed air against blades 56 of power turbine 20. The unburned air entering the annular space between tubular shell 47 and liner 47a flows in large part through openings 470 into secondary combustion chamber 48 and mixes with fuel drawn into the fast flowing products from the centrally disposed fuel supply pipe 59 fitted'at its end with a fuel dispensing wick assembly 695 This fuel is consumed within chamber 48 and the resulting products of combustion along with those entering from primary chamber 49 then flow through nozzles 60 against blades 61 of turbine runner 31 to drive compressor impeller 35. Nozzles 60 are here shown as mounted between shell 47 and 'a' shroud cap 63 positioned opposite the left hand end of runner 31- in the manner clearly shown in FIGURE 2. The low pressure products of combustion discharging axially to the right from blades 61 of runner 31 enter the left end of a series of passages 65. These passages are formed by a ring of long flat tubes 66 disposed radially about the midportion of turbo-compressor '25 and best understood from FIGURES 2 and 3. Tubes 66 extend through openings in annular shell 47 and their long narrow outer ends open through engine housing 18 into a chamber 67 formed by a ring-like housing 68 suitably secured to the engine housing. j

From the foregoing it will be recognized that the ho gases, in passing through tubes 66, give up a major portion .of the heat therein to the relatively cool compressed air fiovin'ng about the exterior surfaces of these tubes en route from compressor outlet 42 to the two combustion chambers 48, 49. Additional heat exchange with the compressed air occurs as the exhaust gases flow through chamber 67 toward outlet duct 70.

p Also preferably located in chamber 67 are several con-- volutions of a fuel supply pipe 75 having its outerend 76 connected via a suitable pressure regulator'77 to .a

discharge end of fuel pipe 75 extends into a specially con- 7 structed high temperature wick device and flame holder 1 designated generally 69. Although not .so shown, it will be understood that fuel distributing pipe-59 for secondary combustionchamber'48 may also have its inlet end in communication with the fuel preheatingcoil 75.

The combined flame holder and fuel distributing Wick 1 devices 69, 69' are illustrated in all essential respects in 'FIGURE 6. This device is generally cylindrical and has '126 are multiple layers 129 of high temperature wicking such as quartz or glass fibers suitably interwined as by felting or weaving the same into a fabric. 7 This wicking material formed of a multiplicity of glass or quartz filaments is found to provide a highly effective wick operating to distribute a large volume of liquid fuel over a wide surface area directly in the combustion chamber and fully.

exposed to the heat thereof. 7 V The wicking proper is held in assembled position against cylinder 126 in major part by a wrapping of stainless wire 'mesh 130 reinforced and stiffened by attached strips of metal 131 and secured to main body cylinder 126 by staples, wire ties or the like 132 passing through perforations in-the body cylinder. The wicking is additionally where within the principles of thisinvention;

held against cylinder 126 by inner and outer fuel' distributing split ringmembers135, 136, respectively, of similar construction but having oppositely contouredcrosssections of the type best shown in FIGURE 6. Each has a wide interior flow channel the side walls of which have axially and oppositely flaring lips 137. The adjacent ends of these ring members overalp and are provided with radiallugs 138 and threaded clamping devices.

The outer. 1

ring 135 is equipped with a clamping device, such as an ordinary nut and bolt, by which this ring can be'contracted with its lips compressing the wicking against main body cylinder 126, whereas inner ring 136 is equipped with a threaded adjuster 139 having left and right hand threads I and operating when rotated to expand ring 136 thereby compressing wicking 129 against the interior surface. of cylinder 126.

Since it is desirable to supply pressurized fuel to the liquid distributing channels extending along the interior of rings.135, 136 to assure uniform and thorough distribution through all parts of the wick as well as for:

flushing away sediment and foreign particles, it is important that lips 137 of the rings compress the wicking sufficiently to prevent escape of fuel past the lips except along and through. the wick itself. Proper tightening of rings 135, 136 is found to provide a fully satisfactory 7 smaller secondary combustion chamber 48 .is identical with wick 69 except for size.

Referring more particularly to FIGURE 2, it is pointed Additional control if' out that a most important feature of the invention resides in the provision of controllable. bypass means including bleed port. means for bleeding or bypassing regu'-.

lated portions only of thepressurized gas in a path bypassing the power output turbine 20 or through an alternate path bypassing both this turbine as well as both combustion chambers. These bleeder port. and bypass facilities have multiple functions and purposes as will be explained'in greater detail below following a description of suitablestructural embodiments of the means re ferred to. g V

As herein shown, the bleeder or bypass means isshown located at the opposite ends of the two" combustion chamstood that these passages or ports may be located elseor ports functioning primarily to compensate for unstable compressor operating conditions may be. located at any point downstream from the-discharge of the compressor.-

The heat present in the air or gas bled therethrough is utilized in some downstream component of the engine rather than beingwasted' to the atmosphere as. proposed heretofore. However, in the preferred embodiment, and as herein illustrated, all bleeding and bypassing of compressed gas is into the inner or preheating combustion chamber 48 for beneficial use in supplying power required for auxiliaries of the engine, as for example, to drive tur-;

nine 61 connected to the compressor. To this end', annular shell 47 separating combustion chambers 48 and 49 l is provided with one or more bypass openings a, 801). As herein shown, there are two such openings 80 disposed generally at the opposite ends, of the inner combustion chamber 48.

This arrangement of the power control valves 81a, 81b provides a wide range of flexibility in performance and operating characteristics since the operator is enabled to bers 48, 49 as viewedin FIGURE 1, but it isto'be under.-

The port spill any desired relative proportions of either hot or cold gas from'the upstream side of the power turbine. While heretofore it has been thought essential to cut off or restrict flow to and through the power turbine to regulate its power output in an effective and reliable manner, this invention has disclosed this to be unnecessary and to involve needless complications. Thus, the bleeder devices of this invention are, in effect, adjustable pressure regulators for varying the effective pressure differential across the turbine to be regulated. Only that portion of the gas need be bled around the turbine being controlled required to provide the desired change in its power output, the remainder of the gas continuing to flow in the normal flow passage without need for changing the size or flow characteristics of this latter flow passage. It will therefore be recognized that this novel principle as herein applied permits one to achieve full range power control without change of any kind in the main and normal gas flow channels and by use of a bleeder control having a maximum flow capacity substantially less than that of the normal main passage. Substantially greater reductions in the size of the bleeder facilities are feasible by sacrificing the capability of each bleeder to provide full range control of the power output; in other words, by making them so small that partial opening of both bleeders is necessary to achieve full power cutoff. Maximum deceleration is achieved by opening port 8012 to bleed relatively cold fuelless air into the discharge end of inner combustion chamber 48. This cold air is of little avail in driving the compressor turbine with the result that the compressor performance falls off to a marked degree thereby further reducing the volume of air supplied to the engine by the compressor.

Bypass ports 80a, 80b are arranged to be closed by any suitable flow regulating means, as for example, poppet type valves 81a, 81b having stems 82 reciprocally supported by appropriate structures such as bosses 83 and an associated operating piston 85 and piston housings 86 mounted on engine housing 18. As here shown, valves 81a, 81b 'are normally urged closed by compression springs 84 encircling stems S2 with one end bearing against the outer end of housings 86 and the other end bearing against pistons 85. Pistons 85 have a fluid-tight seal with the interior of cylinders 86 and are arranged to be operated in opposition to springs 84 under fluid pressure supplied through tubing 87 leading to actuating control means to be described in detail presently.

Preferably, there is also provided a third or compensator port 80 here shown as disposed at the lower rear end of the engine and serving as a separately controllable bleeder port for bleeding pressurized fluid from the discharge end of the compressor into some lower pressure portion of the engine having use for the available energy and as necessary to trim the compressor and render it stable. Although it is not necessary, bleeder port 80' is here shown as provided with controllable valve means .81 and an externally accessible finely regulatable control means therefor such as that illustrated in FIGURE 2. As there shown, an enlargement on the outer end of valve stem 82 is threaded and mated with threads internally of housing 85'. The port or ports 80' may be relatively small since the purpose and function of these is to bleed air from the passage in direct communication with the discharge of the compressor to reduce the pressure of this fluid sufficiently to prevent surging, pulsing and unstable operation of the compressor.

As is well known to those familiar with compressor design and operation, if the pressure in the discharge passage of the compressor rises above a critical value there is a tendency for a backflow of air which gives rise to pulsing, surging, vibration and a decrease in the operating efficiency of the compressor. In fact it is not uncommon for the compressor to become partially inoperative and/ or for serious vibration conditions to arise. Such conditions can occur under various operating conditions including varying temperature conditions in the combustion chamber, varying output loads on the power turbine, and high air temperatures of the air entering the compressor and others.

By applying a tool to the noncircular outer end of valve stem 82' valve 81 can be adjusted to a fine degree and as necessary to stabilize each individual engine and its compressor and maintain the compressor at peak operating efiiciency free of surging, pulsing and unstable operation under idling and all power output conditions.

It is also to be understood that this invention includes the concept of drilling small bleeder ports similar to ports in the wall of the housing leading high pressure fluid from the compressor discharge to a point of use, such drill ports having the necessary area required to compensate for the same conditions as valve 81', namely, variations in the manufacturing tolerances or performance characteristics of a particular operating environment for the compressor. For example, if it is found that a particular completed assembly delivers compressed fluid at a slight excess pressure tending to cause surging or pulsing or the like unstable condition in the compressor, then the assembly may be rendered stable merely by providing a small bleed port of the requisite size for wasting excess fluid to the exterior of the engine.

Referring more particularly to FIGURES 4 and 5 there is shown diagrammatically one suitable control arrangement for the described gas turbine engine. Fuel stored in a suitable tank is connected to a pump 101 by conduit 102. Desirably, the discharge side of the pump is connected by a conduit 103 and a suitable pressure relief valve 104 to the tank in order that fuel in excess of actual requirements is returned to the tank while assuring a constant pressure on the fuel flowing to the engine from the discharge side of the pump. The pressurized fuel line 105 includes an adjustable needle valve 106 urged toward closed position by spring 107. Needle valve 106 is connected through a suitable operating lever means 108 to an accelerator pedal 17a located closely beside accelerator pedal 17 controlling the position of bypass valve 81a in engine 10 and the hand operated member 17' being similarly operable to control'bypass valve 81b. After the fuel passes needle valve 106 it continues through conduit 105 into manually-controlled three-way valve 110 con veniently mounted adjacent the operator, as on the dashboard of vehicle 11.

Manually-controlled valve 110 is provided with a rotary plug 111 having an operating handle 112. Plug 111 is provided with the usual three-way intersecting passages variously rotatable into registry with conduits 59, 79 leading respectively to the primary combustion chamber nozzle 59 and to the primary combustion chamber nozzles 79. From the foregoing it will be understood that accelerator pedal 17a is operable to adjust needle valve 106 to regulate the quantity of fuel flowing to the engine whereas manual valve 110 is adjustable to one of three operating positions to permit fuel flow to either burner or to both. Thus valve 110 has four principal positions each of which is illustrated in FIGURE 5. When the valve is in the position shown in the upper diagram, no fuel can flow to either combustion chamber. If the valve plug is rotated 180 degrees, fuel flows only to the secondary or reheat combustion chamber 48. If the valve plug is rotated 90 degrees clockwise from the last mentioned position then it will be understood that fuel flows to both the primary and secondary combustion chambers. And lastly, if the valve is rotated clockwise 180 degrees from the last described position, fuel is supplied only to the outer or primary combustion chamber 49.

It should also be pointed out in connection with-FIG- URE 4 that the other control pedal 17 is arranged to actuate a master hydraulic cylinder 115 connected through conduits 87 with the outer ends of actuating cylinder 86 for the bypass or unloading valve 81a. Likewise hand control 17' will be understood as effective through an identical device 115' to open and adjust the alternate bypass valve 8112. A suitable compression spring 116 underlies hand control 17' and both accelerator pedals and normally urges each to their respective extended positions wherein valves 81a and 81b are closed. Operation of the valves operatively connected with each is elfected by depressing the associated control 17" or either or both accelerator pedals 17, 17a.

It is further pointed out that each of the combustion chambers is provided with suitable igniter means for initiating operation such as glow plug igniters 118 and Igniter 118 has its active end positioned to ignite.

119. fuel present in wick 69' whereas the active end of igniter 119 is similarly positioned with respect to fuel present in wick 69.

In concluding the detailed description of one typical embodimentof the invention engine it will be understood provided with bypass port facilities bearing important relationships to the areas of the respective inlet nozzles or.

ports of the two turbines. In general, all bypass ports designed to control the p-ower output of the power turbine throughout its full load range should have a flow crosssection greater than inlet nozzles 55 of the power turbine and equal to or slightly greater than the total area of inlet nozzles 60 of turbine 61 driving the air compressor. For practical purposes a bypass port area intermediate that of the two turbine inlets provides for' full range power control as this bypass capacity taken with normal losses serves to' bypass as much gas past the power turbine as can be accommodated by the inlet nozzles to the compressor turbineand results in zero pressure differential across the power turbine. Under these conditions there is no flow through the latter and'consequently no power is produced by the power turbine.

Usually .it is desirable that the two sets of bypass valves at the opposite ends of the two combustion chambers each be large enough to provide full range power control to the 7 that an engine suitably designed to propel a conventional passenger automobile and rated at 180-200 horsepower is merous problems inherent in the use of such high pressure spray nozzles in that pressures only slightly above the compression ratio pressure is required since this is adequate to permit saturationof the wicking by capillary action from the constant liquid supply maintained interiorly of channel-shaped fuel distributors 135,. 136 (FIGURE 6). -In the engine here disclosed, a fuel-pressure not in excess of 50 p.s.i. is entirely adequate, it being borne in mind that it must always slightly exceed the particular internal pressure of the respective combustion chambers or else liquid cannot reach the wick devices.

Operation and control of the engine The mode of starting and operating the described gas outer concentric chamber housing the primary combustion chamber 49. Preferably, during starting bypass valve 81a is held open by depressing control pedal 17 allowing part of the compressed air to flow through port 80a and directly into secondary combustion chamber 48 and another portion to pass through power turbine runner 20.

end that each alone can be used for this purpose; ln this case, simultaneous use of bothsets of valves provides assurance of excess and instantly responsive power control capability; Although only single valves 80a and 8012 have been shown in the drawings, it will be understood that two or more of each are desirably presentparti'cular ly in all except small capacity engines, and these are appropriately distributed about the circumference of the engine. Irrespective of the number used, the total capacity of the ports controlled need not exceed the proportions set forth above since the maximum useful capacity isthe flow capacity of the compressor turbine nozzles 60. In an engine of 180-200 horsepower, one might use, by way of example, a power turbine nozzle area of say 2.5 square inches and a compressor turbine'nozzle'area of 5 square inches. In'this case each'set of hot gas bypass valves 8011 could be provided with a port area of not substantially in excess of 5 square inches, and the same size for the area of port-s'80b. The bypass ports need never be larger than the area of ports 60 because there is never need for bypassing more gas than can flow through the downstream ports 60. However, it will be quite apparent that this maximum bypass port size is many times smaller than the size of the engine flow passages generally, and particularly those leading to and from the bypass ports. For this reason all problems associated with the use of valves to control engine power by bypassing regulated quantities of gas around the power turbine are, greatly minimized as is the control of these valves.

V disadvantages well known to those skilled in this art. The

fuel dispensing wicking of this invention avoids the nu- Once this air flow is established the operator depresses accelerator pedal 17a to open needle valve 106 and manipulates handle 112 of the manual valve 110 to a position supplying fuel only to inner smaller wicking 69 by way of conduit 59. This fuel is ignited by plug 118 and soon provides a supply of hot pressurized gas to operate turbine 61 driving air compressor 25 whereupon starter motor may be de-enerized..

The engine may continue to operate in this manner under idling conditions and with only the inner burner operating until there is a need for useful power from turbine 20. -In the meantime the hot gases issuing fromturbine 61 driving the compressor flow through heat exchanger passages 65' thereby pre-heating the compressed air enroute to primary combustion chamber 49, the hot gases flowing about passages 65 and into annular chamber 67 containing the fuel pre-heater coils 75.

During engine idling conditions with only innercom bustion chamber 48 in operation, little or no useful power is suppl ied to the load by power turbine 20, since the open:

condition of bypass v-alves 81a results in an inadequate pressure diiferential across the power turbine to drive it. It will be understood that during engine idling operation waste heat from inner combustion chamber warms the outer combustion chamber and the engine generally as the compressor accelerates towards its normal high-operate ing speed. Accordingly, upon the supply of fuel to the primary combustion chamber through wicking assembly 6 9 and the partial or full closure of bypass valve 81a,the engine is in instant readiness to start to provide power from turbine 20. If power production is desired as.

quickly as possible, operation of the primary combustion chamber may be intiated along with or shortly following activation of inner chamber 48.

In connection with the foregoingit will be under,- stood that initiation of combustion in outer chamber 47 is preceded by the operator shifting manual valve to the position shown in the third diagram of FIGURE -5'to supply fuel to both chambers 48 and 49.

When operating under the conditions last described the power output of the engine is controllable selectively and at the'operators option in any of several different ans-3,49%

or both, to position bleeder valves 81a, 81b as required to provide any desired power output. As will be apparent, the power output of turbine 20 will be dependent upon the proportions of the hot'pressurized gases passing through the turbine relative to those shunted past this turbine by valves 81a, 81b. Thus, when valves 81a, 81b are fully open turbine 20 is inelfective to deliver power to the load whereas in intermediate adjusted positions of these valves, the turbine is effective to deliver power to the load at a speed and in an amount depending primarily on the adjusted position of these valves and the amount of fuel delivered to the primary and secondary combustion chambers. If the valves are fully closed as shown in FIGURE 2, then the power developed by turbine runner 20 is dependent upon the fuel admitted to the two combustion chambers.

The advantages attending the use of valve 81b to control power output have been referred to above and need not be repeated save to mention that both serve to route gases around the turbine to control its output but valve 81a assures a flow of all gas through both combustion chambers, whereas valve 81b routes relatively cold air free of fuel vapor past the turbine and both combustion chambers. It will therefore be appreciated that a change in power output, particularly in deceleration, is obtainable substantially instantaneously by manipulating the latter valve.

Alternatively, the power output is controllable by closing valves 81a, 81b and adjusting the position of accelerator pedal 17a to control needle valve 106 and thereby the quantity of fuel flowing to the respective combustion chambers. Further control is provided by adjusting the position of manual valve 110. Still another control mode involves regulation and control of all valves and of both pedals 17 and 17a.

Under operating conditions wherein full power output of the engine is not required, it is customary to position manual valve 110 so that fuel is supplied only to the main or primary combustion chamber 49, no fuel being supplied to inner chamber 48. Under these conditions the power output is less than the maximum available power and the hot gases discharging from the power turbine continue straight through the inner chamber and into nozzles 60 to energize the compressor driving turbine 61 following which these spent gases pass in heat exchange with the compressed air flowing to the primary combustion chamber. Variation in the speed of vehicle 11 is then achieved by adjusting accelerator 17a to vary the position of the fuel rate control valve 106; alternatively, accelerator 17 can be operated to adjust the open position of bypass valve 81a. Immediately upon need for extra power, the operator shifts manual valve 110 to a position supplying fuel to both combustion chambers.

As will be recognized from the foregoing, the engine performance characteristics are unusual both as respects their range, flexibility and variety. Power response is particularly unique and attainable in a very brief period because of the provision of the inner combustion chamber which permits the use of all initially available energy to drive the turbo compressor thereby to accelerate this unit to partial or full speed as desired very quickly and efiiciently. Simultaneously, or in time delay relation, the primary combustion chamber can be placed in operation with the result that high power output is available almost instantly simply by adjusting bypass valves 81 toward closed position. The only lag in power response is that slight amount associated with the acceleration of the low inertia power turbine runner. Almost instant speed response is obtainable through adjustment of the easily and finely adjustable bypass valves. Wide range but considerably slow speed response is also attainable by adjusting the fuel rate by means of needle valve 106 and accelerator 17a.

It is pointed out and emphasized that all air entering the engine flows through the heat exchanger as well as through both the primary and secondary combustion chambers and thence through the turbine driving the air compressor. This is true, irrespective of whether the power output turbine 20 is being driven at full capacity, partial capacity, idling, or is standing still owing to and depending upon the adjustment of bypass valves 81a, 81b. If the latter valves are fully open then the flow taking place through the power turbine is ineffective to drive the turbine. However, irrespective of the position of the valves the only inlet to the engine is by way of air compressor inlet 40 and the sole outlet from the engine is by way of the turbine driving the compressor. Furthermore, and of very considerable importance is the fact that the overall operating efliciency of various components of the engine remains at a very high level in substantially all adjusted positions of valves 81a, 81b owing in large measure to the described circuit through which the gases are constrained to flow, the highly beneficial effects of the reheating principle, and the extremely short detour path (i.e., through ports a, 8012) taken by the gases during idling and fractional power requirement operation and while continuing to operate the compressor in a stable manner at high efliciency free of pulsing, surging or the like.

While the particular gas turbine engine herein shown and disclosed in detail is fully capable of attaining the objects and providing the advantages hereinbefore stated, it is to be understood that it is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as defined in the appended claims.

I claim:

1. A fuel vaporizing and flame-holding device designed to be located interiorly of a gas turbine combustion chamber and to withstand the high temperatures customarily existing in such chambers, said device having a thin wide-area rigid main body, multiple layers of noncombustible filaments arranged to feed fuel therealong by capillary action held assembled against the opposite sides of said main body, a rigid reticulated protective cover for said multiple layers, and liquid fuel distributing means held against said layers of filaments on either side of said main body and in open communication with underlying ones of said filaments and extending crosswise thereof between the opposite ends of said main body for supplying fuel to said layers of filaments.

2. A fuel vaporizing and flame-holding device as defined in claim 1 characterized in that said rigid main body is tubular and provided with radially disposed flanges at its opposite ends at least one of which projects outwardly beyond the exterior sides of said capillary filaments.

3. A fuel vaporizing and flame-holding device as defined in claim 1 characterized in that said rigid main body is tubular and in that said fuel distributing means comprises inner and outer split ring bands of channel shape in cross section having their edges holding the adjacent layers of filaments pressed against the juxtaposed surfaces of said main body.

4. A combined fuel distributor and flame holder for use in the combustion chamber of a gas turbine engine comprising, a thin-walled tubular body of high temperature material having flanges at the opposite ends thereof projecting laterally in opposite directions from the end portions thereof, high temperature fibrous wicking mounted against the inner and outer surfaces of said tubular body and extending substantially from end-to-end thereof, means holding said wicking in assembled position against said tubular body, and means for distributing fuel -to said wicking circumferential and between the opposite ends of said tubular body.

1 5 5. A combined fuel distributor and flame holder as define-d in claim 4 characterized in that said wicking includes quartz fibers felted together.

6. A combined fuel distributor and flame holder as defined in claim 4 characterized in the provision of a foraminous coverfor said Wicking eifective in holding the same snugly assembled against the opposite sides thereof. 1 7.- A combined fuel distributor and flame holder as de-. fined in claim 4 characterized in that said fuel supply and distributing means comprises inner and outer channel shaped members encircling said wick-ing on the opposite sides of said tubular body, the outer one of said rings including means for contracting the same against the wicking on the exterior of said tubular body and the inner one of said members including means for expanding the same against the Wicking on the interior side of said tubular body, and means for supplying fuel to both of said chan-' nel-shaped members for absorption and distribution to i said wicking.

References Cited by the Examiner UNITED STATES PATENTS CARLTON R. CROYLE, Primary Examiner. RALPH D. BLAKESLEE, Examiner. MARK NEWMAN, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,283,497 November 8, 1966 Leo I. Kaplan It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 3, line 12, for "outer" read inner Attest:

EDWARD J. BRENNER Commissioner of Patents ERNEST W. SWIDER Attesting Officer 

4. A COMBINED FUEL DISTRIBUTOR AND FLAME HOLDER FOR USE IN THE COMBUSTION CHAMBER OF A GAS TURBINE ENGINE COMPRISING, A THIN-WALLED TUBULAR BODY OF HIGH TEMPERATURE MATERIAL HAVING FLANGES AT THE OPPOSITE ENDS THEREOF PROJECTING LATERALLY IN OPPOSITE DIRECTIONS FROM THE END PORTIONS THEREOF, HIGH TEMPERATURE FIBROUS WICKING MOUNTED AGAINST THE INNER AND OUTER SURFACES OF SAID TUBULAR BODY AND EXTENDING SUBSTANTIALLY FROM END-TO-END THEREOF, MEANS HOLDING SAID WICKING IN ASSEMBLED POSITION AGAINST SAID TUBULAR BODY, AND MEANS FOR DISTRIBUTING FUEL TO SAID WICKING CIRCUMFERENTIAL AND BETWEEN THE OPPOSITE ENDS OF SAID TUBULAR BODY. 